The disclosure relates to an electric drive control device, electric drive control method, and program of same.
Conventionally, an electric drive device mounted in a vehicle, such as an electric vehicle, for example, and designed to generate drive motor torque, i.e., torque of a drive motor which is an electric machine, transmits the drive motor torque to driven wheels, generating driving force.
Also, an electric drive device mounted in a hybrid type electric vehicle, which transmits a portion of engine torque, i.e., torque generated by the engine, to a generator (generator/motor) which is a first electric machine, and the rest of the engine torque to the driven wheels, is provided with a planetary gear unit having a sun gear, a ring gear, and a carrier. The carrier is coupled to the engine, the ring gear is coupled to the driven wheels, and the sun gear is coupled to the generator, such that rotation output from the ring gear and a drive motor, which is a second electric machine, is transmitted to the driven wheels, generating driving force.
Moreover, the drive motor control device, which is an electric machine control device, is provided in the electric vehicle, and the generator control device serving as a first electric machine control device, as well as a drive motor control device serving as a second electric machine control device, is provided in the hybrid type electric vehicle. A pulse width modulation signal for a U phase, a V phase, and a W phase generated in the generator control device and the drive motor control devices is sent to an inverter. The inverter then generates phase currents, i.e., currents for the U phase, V phase, and W phase, which are supplied to each stator coil of the generator and the drive motors. As a result, asynchronous pulse width modulation (PWM) control is performed which drives both the generator so that generator torque, i.e., torque generated by the generator, is generated, and the drive motor so that drive motor torque is generated.
In the drive motor control device, for example, a d axis is established in a direction of a pair of magnetic poles in a rotor, and a q axis is established in a direction perpendicular to the d axis based on the positions of the magnetic poles of the rotor. Feedback control is then performed according to a vector control calculation on the d-q axis.
Therefore, the drive motor control device detects the current supplied to each stator coil, the positions of the magnetic poles (hereinafter referred to simply as “magnetic pole position”) of the rotor, the direct current voltage on the input side of the inverter, and the like. The detected current is converted into a d-axis current and a q-axis current based on the magnetic pole position. A d-axis current command value indicative of the d-axis current and a q-axis current command value indicative of the q-axis current are then calculated based on the direct current voltage, drive motor target torque indicative of a target value of the drive motor torque, and the like. The drive motor control device then generates a d-axis voltage command value and a q-axis voltage command value so that the difference between the d-axis current and the d-axis current command value, as well as the difference between the q-axis current and the q-axis current command value, become zero (0). The drive motor control device then generates voltage command values by converting the d-axis voltage command value and the q-axis voltage command value into voltage command values for the U phase, the V phase, and the W phase based on the magnetic pole position. The drive motor control device then generates the pulse width modulation signals based on the voltage command values.
When performing the vector control calculation, the d-axis current and the q-axis current are both estimated based on a voltage equation on the d-q axis. The estimated d-axis current and q-axis current are then used to calculate the aforementioned differences. A d-axis inductance Ld and a q-axis inductance Lq of the drive motor are used as parameters to prevent the d-axis current and the q-axis current from interfering with one another (i.e., to isolate them from one another) in order to increase the accuracy of the feedback control (see Japanese Patent Application Laid Open No. 5-130710, for example).
When a motor employing both magnet torque and reluctance torque is used as the drive motor, a salient pole is provided to make a permanent magnet, which generates the magnet torque on the d-axis of the rotor, generate reluctance torque on the q-axis. The magnet torque and the reluctance torque can be changed by changing current phases indicative of the position of an electromagnet created by supplying current to a stator coil.
In particular, if a motor having an asymmetrical salient pole, i.e., if an asymmetrical salient pole motor, is used, magnet torque is able to be sufficiently utilized and total torque which is the sum of the magnet torque and the reluctance torque is able to be sufficiently generated. Moreover, the current phase when field weakening control is performed may be reduced, thereby making it possible to prevent a decrease in the total torque (see Japanese Patent Application Laid Open No. 2004-32947 (family member in U.S. patent Publication 2005/0017588 A1), for example).